Restore support for explicitly referenced CMakeLists.txt sources

Since commit v3.11.0-rc1~467^2 (VS,Xcode: Add CMakeLists.txt sources
without mutating targets, 2017-10-18) we do not add `CMakeLists.txt` to
target sources but instead generate references to them directly.  This
broke projects that explicitly specify their `CMakeLists.txt` file as a
source file because the explicit entry is no longer consolidated with
the generated one.

Teach the relevant generators to avoid duplicating `CMakeLists.txt`
source references and add test cases.

Fixes: #17828

1 files changed, 2 insertions, 0 deletions

diff --git a/Source/cmGlobalXCodeGenerator.h b/Source/cmGlobalXCodeGenerator.h
index b45887e..7c51177 100644
--- a/Source/cmGlobalXCodeGenerator.h
+++ b/Source/cmGlobalXCodeGenerator.h
@@ -198,6 +198,8 @@ private:
                                           cmGeneratorTarget* target);
   cmXCodeObject* CreateXCodeSourceFile(cmLocalGenerator* gen, cmSourceFile* sf,
                                        cmGeneratorTarget* gtgt);
+  void AddXCodeProjBuildRule(cmGeneratorTarget* target,
+                             std::vector<cmSourceFile*>& sources) const;
   bool CreateXCodeTargets(cmLocalGenerator* gen, std::vector<cmXCodeObject*>&);
   bool IsHeaderFile(cmSourceFile*);
   void AddDependTarget(cmXCodeObject* target, cmXCodeObject* dependTarget);